Here you will learn top 10 linux shell scripting interview questions with answers. Please practice these questions as 90% questions will be asked during in linux admin interview.
Q:1 How many types of variables used in a shell Script?
Ans: There are two types of variables used in Shell Scripts:
- System Variables
- User defined Variables
- System variables are defined or created by OS itself. These variables are generally defined in Capital Letters and we can check these variables by ‘printenv’ command.
LESSOPEN=| /usr/bin/lesspipe %s
LESSCLOSE=/usr/bin/lesspipe %s %s
- User defined variables are created by users and the values of variables can be viewed by using the command “echo $”.
var3=“testing not done yet”
Q:2 How to check previous command execution status in shell script ?
Ans: While writing a shell script , if you want to check previous command is executed successfully or not , then we use “ echo $?” with if statement to check the exit status of previously executed command.
[email protected]:~# ls /usr/bin/pwd /usr/bin/pwd [email protected]:~# echo $? 0 If exit status is 0 , then command was executed successfully [email protected]:~# ls /usr/bin/linux ls: cannot access /usr/bin/linux: No such file or directory [email protected]:~# echo $? 2 If the exit status is other than 0, then we can say command is not executed successfully.
Q:3 What is the basic syntax of WHILE loop in shell scripting ?
Ans: The while loop repeats its block of commands a number of times. The while loop iterates until its while condition is no longer true. The basic syntax is .
while [ test_condition ]
Q:4 What is the syntax of FOR loop in shell script ?
Ans: Basic Syntax of for loop is given below :
for variable in list_of_items
Q:5 How to put comments in your bash shell script?
Ans: Comments are the messages for other users that describe the functionality of a shell script. To put comments in your script, start each comment line with a hash sign (#) as below.
#This is a comment
#The below command show the logged in user
echo “I am $USER”
Q:6 How to get input from the command terminal in a shell script?
Ans: ‘read’ command reads in data from the command line terminal . The read command takes input whatever the user types and places the text into the variable you name as shown below.
# vim /tmp/test.sh #!/bin/bash echo ‘Please enter your name’ read name echo “My Name is $name” #./test.sh Please enter your name Ravindra My Name is Ravindra
Q:7 What is the syntax of IF ELSE Conditionals in shell script?
Ans: The if..else statement is the control statement that allows shell to make correct decision out of two conditions. The syntax as shown below.
if [ expression ]
Statement(s) to be executed if expression is true
Statement(s) to be executed if expression is not true
Q:8. What is Shebang in shell script?
Ans: Shebang is a # sign followed by an exclamation i.e. !. Generally, this can be seen at the top of the script. Usually, a developer or administrator uses this to avoid repetitive work. Shebang determines the location of the engine which is to be used in order to execute the script.
Here ‘#’ symbol is called hash and ‘!’ is called a bang.
The above line tells which shell to use.
Q:9 What is the significance of $# ?
Ans: $# shows the count of the arguments passed to a script.
Q:10 What is the difference between $* and [email protected] ?
Ans: [email protected] considers each quoted arguments as separate arguments whereas $* will consider the entire set of positional parameters as single string.
Hence, you have gone through top 10 linux shell scripting interview questions . I hope you are feeling confident.
I hope I helped.. Thanks!!!